A valve control device is well-known, which has a valve unit disposed in a cooling water circuit of an internal-combustion engine and a control part. The valve unit is assembled in the cooling water circuit to increase or decrease the flow rate of the cooling water to the internal-combustion engine, and the control part controls operation of the valve unit. The valve unit has an electric motor to which voltage is applied by the control part, and a valve object driven to rotate by the output of the electric motor to increase or decrease the flow rate of the cooling water to the internal-combustion engine. In the cooling water circuit, cooling water circulates also to other apparatus (for example, heater core of an air-conditioner for a vehicle, and/or oil cooler for lubricating oil of the internal-combustion engine) other than the internal-combustion engine. The circulation of the cooling water to the other apparatus is started or stopped by a valve device other than the valve control device.
In recent years, the valve control device for circulation to the internal-combustion engine and the valve device for circulation to the other apparatus are put together in the cooling water circuit. Patent Literature 1 describes a configuration in which a valve unit of a valve control device is made to have functions starting and stopping the circulation of the cooling water to the other apparatus. Specifically, the housing of the valve object has ports corresponding to the internal-combustion engine and the other apparatus. In response to the rotation angle of the valve object, the flow rate of the cooling water to the internal-combustion engine is increased or decreased, and the circulation of the cooling water to the other apparatus is started and stopped.
However, if a foreign object enters the valve unit, a fault arises in rotation of the valve object. Then, the circulation state of cooling water will shift from a desired state both for the internal-combustion engine and the other apparatus. That is, a foreign object entering the valve unit, in Patent Literature 1, has large influence on both of the internal-combustion engine and the other apparatus. For this reason, it is required to detect a foreign object caught in the valve unit.
In order to detect a foreign object, an over-current detector which detects an over-current to an electric motor, and a torque detection part which detects a torque transmitted to a valve object are well-known (for example, refer to Patent Literatures 2, 3). In Patent Literature 2, a foreign object is detected when the over-current detector detects an over-current. In Patent Literature 3, a foreign object is detected when the torque detection part detects excessive torque. However, the necessity of adding the over-current detector and the torque detection part increases the size of the valve control device.